Self-puncture-sealing covering for fuel-containers



6.1. MURDOCK. SELF PUNCTURE SEALING COVERING FOR FUEL CONTINERS.

APPLICATION FILED JAN. 16. |918.l

Patented Auff. 9,1921.

2 SHEES-SHEET l.

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o m n@ .1. MHRDOCK.

. SELF PuNcTuRE SEALING covEmN@ FOR FUEL CONTAINERS.

` Y APPLICATION HLED JAN. I6, l9l8. lpgl u Patented Aug. 9, 1921..

J .Mmzuocrg 2 SHEETS-SHEET 2.

A QEORGE @Hoz "au GEORGE J'. MURDOCK, OF NEWAlRK, JERSEY.

SELF-PUNCTRE-SEG COVERING FOR' FUEL-CONTAINERS.

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Specification of Letters Patent.

)Patenten nag. a, rear.

Application filed January 16, 191.8.v terial No. 212,053. i

4To all whom ft-may concern.'

Be it known that GEORGE J. MURDOCK, a

citizen of the United States, residing at Newark, in the county of Essex and State of NewJersey, has invented certain new and useful Improvements in Self-Puncture-Sealing Coverings for. Fuel-Containers, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to fuel containing tanks of War aeroplanes, motor trucks, and other self propelled vehicles or other structures having engines using hydrocarbon as a fuel, and generally speaking the object of the invention is to so construct the tank that punctures made therein by projectiles will automatically close so as to prevent the escape. of gasolene, kerosene 0r other liquid hydrocarbons.

After the gasolene tank of a warv aeroplane has been punctured by a-projectile, the gasolene leaks out upon the fuselageand planes and is very liable to catch on fire and even if it' does not catch on tire, puncturing of the tank and the consequent leakage of the fuel puts the aeroplane immediately out of the .fighting and causes its return to its own lines as soon` as possible for repairs. Probably more machines are caused to return to their own' lines because of the loss of gasoleneo through puncture of the tank, than for any other reason and there has been a great loss of life due to this cause. Of course where i the tank of a motor truck, car or other vehicle has been punctured there is -not the same danger to the driver and mechanicians but'even'here the leakage of fuel requires either a stoppage of the car or truck or its return te its base. 1t has been proposed to provide armor for the tanks of aeroplanes, butthis armor, toghe of any value, must have a relatively great weight and this dead load is naturally not desired. 1t has also been proposed to use armor for reserve tanks from which a small amount of gasolene can be drawn if the main tank is punctured, but the puncture of the main tank, as a matter of fact, alwaysv requires that the laeroplane should return to its own lines because of the small amount of gasolene carried in -the reserve tanks, a plug being pulled-out of the main tank when punctured to allow vthe immediate `drainage of this main tank.-4 Many efforts have been made to overcomey this trouble, and tanks so constructed as to. more or 'less prevent the leakage of gasolene after the puncture of the tank by a projectile, formthe subects of two applications for patents by me, led respectively on the 7th day of February, and on the 23rdv day of June, 1917, Serial Number 176,591. The tanks which form the subject matter of these applications, however, have the objectionthat they are relatively heavy and it is to avoid this excess weight in the tanks and further to provide a tank in which the closing action is more posi- 1917, Serial N o. 147 ,17 0

tive, that l have devised the present inven- This invention is illustrated in the accompanying drawings, wherein: l

Figure'l is a top plan View of a gasolene tank of a common type used in. aeroplanes and constructed in accordanceA with my invention;

Fi 2 is a longitudinal sectional view on the l1ne .2 2 of Fig. l;

Fig. 3 is a sectional view ony theA line 3 3 of Fig. 2 looking toward the top of the gasolene tank to show certain details of construction; I

` Fig. 4; is a fragmentary detail section at a corner of the tank;

Fig. 5 is a section on the line 5-5 of Fig. 2 looking toward the top of the tank ;v

Fig. 6 is a fragmentary lvertical sectional view through the tank wall, showing the manner in which punctures are closed both Fig. 8 is arsection on the line 8.-8 of.`

Fig. 3; I

Fig. 9 is a vertical sectional view of a tank having only certain layers as a protective covering, and

Fig. 10 'is a like view to Fig. 9 showing a tank having a certain other arrangement of layers asia protective covering.

Before detailing the construction of the tank and the manner in which the self-sealing/envelop is applied to the tank, 1 will state the prlnc'iples. upon which my invention is based. ln the course o,f many hundreds of experiments directed to the solution of the problem of providing a self-sealing tank, I have discovered that it is Inecessaryto surround the metallic container vwith a substance which will swell when punctured so that when a projectile passes through the envelopof the tank, the puncture will be caused to close by the expansion of the maliquids terial of the-envelop. ln m previous applications above referred to, haveprovided what may be termed mechanical means for closing these punctures, that is, l have placed around the tank an envelop of rubber or like material which, assoon as the bulletpasses will elastically contract 'and plug the opening through which the projectiles have assed, and in the last filed application l have provided means whereby a plug of .wood is caused to be driven into the puncture in the rubber covering. My presentv application is based, however, on entirely different principles and on the fact that rubber will swell or increase in volume when exposed to the action of gasolene, kerosene or other of the hydrocarbon group or to the vapor of such liquids. Furthermore, I have discovered that the speed of'expansion, that is, the length of time which. it takes for the rubber to swell `up to a certain volume when subjected t0 the action of fluid hydrocarbons, depends upon the extent to which the'rubber is vulcanized and also depends, to a lesser extent, upon the chemicals used in vulcanizing.

In accordance with these facts, l construct -the envelop surrounding the metallic container, and by container l not only refer to a tank but to any duct, tube or chamber which will hold fluid hydrocarbon or through which the fluid passes, of a plurality of.

sheets or layers of rubber, certain of these layers being slightly vulcanized, as by the use of antimony sulidor sulfuret, this layer having the property when so vulcanized of swelling uplrel-atively rapidly. The remainder of the layers of rubber are formedof rubber known as full cured, this rubber being cured with sul-fur in the common way Rubber-.cured with antimony suld or su Afuret is ordinarily red or orange colored while thefull cured rubber, cured with sul" furv bythe commonl process,.1s generally gray. v. While l -have above referred to the use of sulfuret of antimony for slightly vulcanizing therst named element, I do not wish to be limited to this, as my invention doesnot lie in this particular step `Of-slightly vul-v canizing the rubber, but-in -the use Aof 'a\ the manner other chemlknown or slightlyv'ulcanized rubber in hereafter stated and, therefore, cals or agents `which are now which maybe hereafter .known tov aHect the objects hereafter stated may be *y used. 60 thetank or other container, pipe or tube o As before stated, I' f orm the envelop of two elements, namely,. rubber which `has been fully cured -with sulfur and rubber which is slightly vulcanized by antimony sulfuret.

.I have found that. rubber. which has been tically,

of fabric such as duck. duck are disposedy sulfur which, as

and whichwill bring the' rubberzinto such condition as f the tank fully cured, but which is still elastic, is practo4 all intents and purposes, insolub in gasolene or other hydrocarbon. When acted upon by gasolene, in' volume but it will not dissolve.

ln the process of swelling under the action of the'gasolene or other hydrocarbon, it

tensile strength and elasticity .but after its full expansion is attained,rit-d0es not ap'- preciably change. `I have vfound that after fully cured rubber be lene and dried, it will shrink to der its voriginal volume and recover its origiit will slowly swell Y le y absorbs the hydrocarbon and diminishes in 'remaining six months in gasolene, if this f taken out of thegasoy slightly unnal elasticity and tensile strength; 'lt is this peculiar characteristicv which makesA this fully cured rubber of such great value as one 'than the fully cured rubber and the friction caused by the passage of a bullet through it will develop enough heat to cause it to fuse together to some extent Iin thepath made by the projectile. The rate of expansionotl this air cured, partly vulcanized rubber when submitted to fluid hydrocarbon, as well as the extent to which it may be dissolved when brought into contact with fluid hydrocarbon, may readily be governed by controlling the percentage of sulfur-contained init and controlling the extent to which vulcanization ist' carried.

ln Fig. 8, l show diagrammaticallyasection of the envelop which covers the tank or container and 1 this enlarged sectional view, 10 designates anintermedi'atev layer or core @n each side of this layers 1 1 of rubber which has been partlyv vulcanized by vmeans of sul-l fur and which-'s aircured and exterior to these'layers 11 are "r'elativel` Athin la ers 12 of yrubberwhich has been ll cure with elastic but is Apractically insoluble in gasolene. 'These layers arecementeel together in a manner which will be now ldescribed and before stated', is slightly cemented or otherwise attached to the metal.

lic wall of the tank in the manner which will be stated, and these layers form an.

envelop ofrubber extending entirely over continuity and this envelop is also"designed to extend aroundl the outlet pipe -leading from'the gasolene tank and also aroundv that-- portio of the outlet pipe w ich is disposed,

without appreciable solutionof.

' and riveted to the sides 16. In order to acconstructing large units than y drawin may be admitted.

' this being complish this riveting a large opening 17 is originally formed through the top wall so that the workmans head and shoulders The seams are then sweated together as at 18 (see Fig. 4:) and done, a disk 19 is soldered n over the opening 17. This disk or cover may conveniently carry the filling nipple 20 which has the usual screw-threaded stopper. A tank constructed as above described is strong andv has even corners.

rThe self-sealing envelop illustrated in Fig. 8 is applied around the outsideof this tank at all points so as to entirely inclose or cover the wall of the tank. I have found it best in the actual construction of thev tank to wind a single sheet of the full cured rub-y ber entirely around the tank in the manner illustrated in Fig. 2, this rubber 'being wound around from end to end. Before doing this the sheet of full cured rubber 12 is varnished with a flexible cementsuch as shellac varnish insoluble in gasolene. This cement holds the-rubber sheet 12 iirmly to the metal and furthermore acts to localize the action of the gasolene to that particular place in the frubber where the projectile has passed through. Both heads 14 are also to be covered with ya single sheet or layer of the full cured rubber 12, cemented to the heads in the manner above stated. After the body of the tank has been covered with this sheet of full cured rubber 12, a patch 21 is disposed over the joint between the head and body covering. This patch is also of fullcured rubber and is cemented to the layer of full cured rubber by means of the elastic cement above referred to.

, A layer of the antimony sulfuret curedv/ rubber of the quick swelling character .be fore vreferred to is now cemented with rub. ber cement to the inner layer 12 of the fully cured rubber. Preferably', this layer 11 is made up of-a pluralityloflthin sheets of the rubber cured with antimony sulfuret asv these thin sheets are easier tov handle in if a single sheet was used having the full thickness of the layer. IfJ this Iinner layer 11 is made up `of thin sheets these sheets are scored by a fine toothed saw lacross them, then wiped clean with gasolene and allowed to -dry before the sheets lare cemented together with rubber cement. The layer 10 -duck 10 is cemented of cotton duck is then applied to the outside face of the layer 11. This cotton duck is thoroughly impregnated with rubber cement, which is Aallowed to dry before the cotton duck is applied to the layer 11. It

is then cemented to the layer 11 and upon the outer surface of this layerof cotton a seco'nd layer 11 of? the. rubber cured `with antimony sulfuret and having the quick swelling quality above referred to. be formed either of a single sheet of rubber or a plurality of sheets. cemented to eachl other, though it is preferred vto build this outer layer up also of thin sheets. -A fourth outer'layer 11, this fourth layer beingthe outside covering layer and formed of a sheet of fully cured rubber.' These4 sheets 12 are relatively thin in comparison with the layers 11. At the joint between the sheets 12 at the corners of the container, a patch 22 is applied, as illustrated in' Fig. 1i, this patch also being of fully cured rubber. ject of the cotton duck 10 is mainly to secure strength and prevent any stretching of the rubber in applying it to the tank and it is to be understood that while I have 'here-y tofore described the covering of the .tank by first cementing an inner layer 12 to the tank, then cementing an inner layer 11 to the layer 12, then cementing cotton duck to thelayer 11, then Asuccesslvely cementin the outer layers 11 and 12 to the cotton duc and each other, yet I do not wish to limit myself to this, as the envelop might be made by cementing the layers 11 to the cotton duck in the first instance, then cementing the layers 12 to the outer faces of the layers 11 andy then cementing the entire composite sheet so formed to the tank. I prefer the method first described, however.

It is necessary, of course, that means be provided for protecting the outlet pipe leading from the ltank from puncture, that is, providing'means whereby if. this pipe be punctured ,the puncture will be sealed. Where this outlet pipe projects into the' gasolene it is necessary of course, @hat 'the rubber be shielded rom constant contact with the gasolene, as otherwise thegasolene wouldl act deleteriously on thev rubber. Where the pipe extends out of the gasolenetank, however, there is no necessity for protecting the pipe from the action of the gasolene on thel rubber. That portion of the outlet pipe which extends through the top This outer layer 11 may also layer /12 of rubber is now applied lto the j The obof the container an'd into lthe gasolene 1s designated 23. For the purpose of sealing any punctures which may occur' in this por'- lThese layers of rubber extend from the top wallof the container downward nearly to the bottom of the pipe 23 vand a head 24 is dis Osed upon the bottom end of the pipe an over the layers of rubber is disposed a sleeve 25 of metal the upper end of this sleeve being formed with a 'base 26 which is at- Y tached to the-top Wall of the tank by screws,

- unless a puncture occurs.

1 other. y'A metal covering such as 25 is not rivets or in any ,other suitable manner. Thus it will'be seenthat the rubber layers 10, 1'1'and'12a are entirely protected by this sleeve from contact with the gasolene v.necessary in thisv case for the reason before stated and bands of small copper wire 28 are wrapped at intervals around the rubber cover, the coils of each wrapping being soldered together and the purpose of these bands'being to localize the action of the gasolene on the rubber in case of -a puncture.

' myself, however,

. projectile .passing through tank. and the covering thereof 'ln Fig. 2 l have illustrated the fact that the sheets of composite rubber which extend around the bodyI of the tank areA overlapped upon each other as at 29, and that-the'joint thus formed'is covered by a patch 3() of the full cured rubber such as is used for the layers 12. l, ofcourse, do not wish to limit to this manner of forming -this joint and it is obvious that a joint may be formed at Iany other portion `olf the tank.

The action of this self-sealing covering is as follows: ln Fig. 6, l show the action of a thewall of the above the gasolene line; ln this case the puncture is immediately closed, sufficiently to prevent the escape of gasolene vapor, by the elastically contractile character of the rubber and by either the actionl of the gasolene vapor upon the outer and innerlayers 11 and 12 or by the gasolene which may slop about within the' tank as the machine vibrates. The exterior layer, that is, the 'layer 12 which is -next to the tank is insoluble in gasolene and expands slowly under the' action of gasolene vapor and eventually the puncture-y is enno time is the puncture.

tirely closed. v At suflicient however` gasolene vapor.

ln Fig. ,6l show the action lof my improved covering whenpu'nctured by a bullet to permit the leakageof belowfthelevel ofthe'liquid gasolene. As

soon as the biillet passes-through the covering. and the wall, a slight' amount of gasothrough the opening" made by the bullet.

23 to the carbufA do not car lene, due to the pressure 1n the tank, passesY relatively large,

to permit the passage of the projectile and then immediately contracts. The layer of gasolene leaks 'in through the slight puncture in the inner layer 12 and the' hole through the cotton duck allows the liquid to come in contact with both layers 11 of the quick swelling rubber. rThe driyingfeect of the bullet forces the rubber away from 4the duck and thus a small chamber is formed on each side of the duck and immediately surrounding the perforation therethrough and gasolene enters and ills this cavity. The gasolene in this cavity, together with that which enters through the perforation in the inner 'lining causes an initial swelling of the lslightly vulcanized air cured rubber.V

' dered impossible,however',from the' tact that the instant the gasolene comes in contact with the fully cured rubber wall 12, "this rubber' wall immediately surrounding t e puncture. commences to swell, although at -a slower rate than the swelling inv therubbut. the perforation or pasl .sage formed through theenvelop will 'be relatively small because the rubber expandsk ber which is cured by antimony suld.- In

about ten minutes this swelling completely closes vthe puncture through-the tully cured rubber layer 12 and, thereforeno incre fresh gasolene can come into contact with. the layer 0r layers v'11, which by this time yhas assumed the condition of a sti paste with-in the area covered by the puncture, eectively sealing the puncture even though this puncture is larger than one made by a .30 caliber bullet. What is true of the action of the bullet perforating the wall of the tank is also true ofA the action of perforating the pipe For tanks which A are liable `to be punc-l tured by bullets of not more than .45 caliber, I have found vthat the total thickness of the envelop and the metal wall of the tank need not exceed giving a total weight of about 2i pounds per square foot of tank surface. If the tankis designed for use where it is liable to be punctured by projectiles. of f larger caliber than Athe above named, then the thickness and Weightof the rubber composite' envelop vmust beI increased accordingly..

greater cali er thanv .30 ori-.45;

The strength and freedom romclasticity.' It is Ordinarily, however,war aeroplanes f guns shooting projectiles of a l cotton duck 10 is :used to obtainV i l i 70 cotton duck 10 has a clean-cut hole. The

'25 furnishes sufficient inserer not alwaysnecessary, in order to carry my invention into. practical use, however. Thus, for-instance, in Fig. v2 there is no absolute necessity of an intermediate layer of cotton duck,`as the outside metallic sleeve strength to the rubber. Where the rubber is not protected by an outer metallic tube, however, then this interlayer of cotton uck is necessary or the projectile would drive the metal away from the rubber to an injurious extent when emerging if the cotton duck were not used. It may be remarked that in Fig. 4 I have shown the intermediate patches 21 and 22 and the layers of rubber exaggerated and, as a consequence, that the corners ofthe tank are bulged outward. As a matter of fact the corners are Hush, or nearly so, with the wall. This is important as bulging'corners, such as are shown in Fig. 4f, will be in the way and prevent the tank from being placed, as is necessary with present aeroplane constructlon.

The rubber cement which is used for the purpose of holding the layers 11 in contact with each other and in contact with the duck and for impregnating the duck is simply raw rubber dissolved in naphtha. This cement dries up as it dispels the solvent and the surface will cease to be sticky, but it will not stand heat or contact with the hydrocarbons, as vulcanized rubber will. Shellac varnish, before referred to, makes a flexible cement, but I have found .it particularly good in causing the inner layer vto adhere tothe tank wall and when this I shellac varnish is dry,

it is insoluble in gasolene, thus acting to limit the zone of action of the gasolene to the parts immediately surrounding the perforation caused by the projectile.

The cotton duck, which is used in connection with the layers of vulcanized and partly vulcanized rubber, is of considerable importanceas the result of a high power bullet striking the body of gasolene within the container is much greater than where a projectile having a low velocity is used. The tendency of the pro'eetile is to drive a column of gasolene in ront of the bullet and out at the other side of the tank. Gaso# lene like water is almost incompressible. It is not where the bullet goesl in that the trouble is experienced, but where it comes out. Nine times out of ten the bullet will come through sidewise cutting a slit perhaps three-fourths of an inch long with a .30 caliber projectile and the blow'on the gasolene will cotton duck, however, prevents the rubber from being driven away from the tinconvtainer as it otherwise would be on account of its elasticity and prevents the rubberl from being ruptured by the blow on the gasolene. If the duck is not used, the driv- 4the gasolene shrinks back bulge the side of the tank. The,

ing out of the lrubber wall splits the outer tin container in all directions Where duck is used in connection with the layers of rubber, however, this splitting actionploes not occur. I may say that I have tested this tank with all fluid hydrocarbons, in other words, practically all fluids that can. possibly be used in internal combustion engines. All of the fluids ofthe benzene group cause the swelling of the rubber whichv has -been heretofore described'but where other fluids are used, as for instance, alcohol, the puncture will close, not by the action of the fluid itself, but because the heat generated by the passage of the projectile through the semisoluble rubber causes the puncture to close s uliciently tight by fusion, as to withstand any pressure which is likely to be used. rIhis closure as before remarked is most effective where the -rubber is semi-soluble as the further vulcanization is carried, the less sensitive the rubber ris to heat. With the insoluble rubber, the' bulletscut a hole that remains cut and the liquid will leak from say that it would be possible to construct an operative tank with a layer of insoluble with an. outer layer of semi-soluble rubber 11 and finally duck or other suitable material 10 outside of this outer layer. It" is also possible, as illustrated in Fig. 10, to cover a tank and make it more or less operative, as a self-sealing tank by using duck 10 on both sides of the semi-soluble rubber 11. Such a construction, however, makes it difficult to build up the corners properly and is also inferior for use with large caliber projectiles wherea distinct hole is made. Thus in. the form of covering shown in F ig. 9, Ihave found in practical trial that the punctures will not leak even under 15 pounds of air pressure applied on the gasolene within the tank for a period of five hours. When this form of covering is punctured, it will form a carbuncular swelling on. the insoluble rubber side, cloth side. This is the case when the hole is formed by a .30 projectile. Afterward the carbuncular swelling, having expelled to its original state very nearly. With .45 bullets, however, the hole made .is large enough to see Athrough and on ya. pressure tank will not close quickly or entirely for. the soluble rubber washes away through'the large hole in vthe duck almost as.fast as it reaches the perforation, this time being' about fifteen. 1

minutes. With the construction illustrated vrubber 12 immediately next to the container that is on the inside, but not on the tsr.

, as well, 'if not better, when the bullet strikes constantly increases.

at an acute angle than if the bullet strikes the tank at a right angle. The rubber which constitutes the covering will stretch away from the tin when the `bullet enters and the projecile does not cut a slit in it, asit. otherwise would but for the elastic nature ofy the rubber. Whenthe angle of fire isfincreased,

that-is, when- .the angle is relatively acute,-

the tendency ofthe projectile is always todent itself into the tin until it inallypunctures the tiniand passes through. As the angle of the `projectile .to the tank wall becomes more acute, the tendency ofthe bullet to plow into the tin forming a groove, which may equal half the diameter of the bullet, Sometimes this groove will be I2" or more in lengthbefore the bullet finally breaks through. There is never much di'erence in t'he outside appearance of the rubber or cover no matter what angle the bullet strikes, but' of coursefwhen it strikes at an acute angle, the puncture must be. somewhat longer than when it strikes at a right angle. The semi-soluble vrubber which forms the intermediate layer or layers swells upon contact with gasolene no matter what the -shape of the passage through the rubber. lt has beenvmy experience also that 'the plug .formed uponthe'pa'ssage of a bullet through my tank wall or cover will resist considerable more air pressure if made at an acute angle than if made4 at a right angle to the tank, as -the swelling` formed in the intermediate wall. or vwalls. is both longer and larger as this intermediate semisoluble rubber will swell for the entire length of. the groove in the tinmaking a .long tapered plug, whereas when the puncture is straight through the wall, thatis, vat-right 'l I have'hcretofore referred to the layers A ing over a considerable'length oftirn';

angles to the wall,. .thel` plug is relatively short. .The statements made above are not 'based upon theory but are the result of actual` experiments and tests made by'me extend- 11 of rubber as swelling rapidly when exposed to liquids of .the benzene group and to the layers 12 of rubber asswelling slowly. :1t thatboth of the Sheets of rubber treated as before .explained swell relatively@- rapidly ,when compared with ordinary rubber., Caoutchouc or raw. rubber swells only slightly before it begins- With the form of tank herewithA .to-dissolve when-in contact with liquids ofl the benzene group, and this swelling is very Aslow in comparison with rubber that has been even slightly vulcanized. Meanwhile, the unvulcanized, raw rubber, whileit is swelling, is also dissolving so that in a short time it is entirely destroyed4 as a mass. Ordinary sheet rubber' as usually found on the market does not swell to any-useful extent when-in contact with gasolene and the swelling takes place at a Vvery slow speed. Furthermore', this ordinary sheet rubber, while it is for all practical purposes insoluble in the' gasolene, whenl submitted to the vaction of gasolene or any. liquid of the benzene group, breaksup and has a cheesy quality. Ordinary sheetrubber, las before explained, swells somewhat. on contact with gasolene, lbut this swelling is at a very slow rate. Both the layers 11 and 12 of my covering, however, swell'rapidly relative to this ordinary sheet rubber and caoutchouc so that where my covering is applied to a tank, the wound' inthe tank wall will heal or seal itself in a few minutes, whereas -were ordinary sheet rubber used, which is of comparatively small elasticity andl has but a small capacity to swell, the puncture would not become sealed sufiiciently to accomplish the desired result.

' It is to be also noted that the degree to which vulcanization is to be carried 1n producing the relatively slow swelling layers 12 maybe definitel, determined by submitting therubber to certain tests. Thus a 100 degree of vulcanization which is proper for these layers 12 is the same as the degree of vulcanization which will give to the rubber maximum elasticity, maximum tensile strength, and maximum expansibility, in 105 Iother words lrubber which -has been vulcanized to an extent where ithas maximum tensile strength, .maximum elasticity and maximum expansibilitv when. in contact with liquids of the benzene group, has been vul- 110 canized .to an extent where it has the qualities nece sary to fit is to form the'layers 12 of my tank. If rubber is vulcanized beyond :the point where itl has maximum elasticity,

'l ized to that degree 'wherein'l the rubber is rendered of maximum elasticity and maximum tensile strength l'when in contact with gasolene, it is practically insoluble in liquids of the benzene group, that is it takes a relaltively long time for the rubber to dissolve in liquids of, the benzene oup. While a practicalinsolubility may e ysecured by a less degree of vulcanization, yet the rubber will not have maximumztenslle strength or when. in contact with gasolene.

maximum-elasticity when in contact with gasolene, nor maximum expansibility in. contact with gasolene. Therefore, it will not be fitted to form the wall 12, which should have. all of these qualities. By testing the .by itself for the reason that it does not swell without dissolution when in contact with gasoline. In other words, it is not practically insoluble but becomes soft, pasty, and unless it is protected by the relatively slow y swelling rubber, would wash away and become so weakened that it would not form any protection for the tank whatsoever. f

It will be noted that in the drawings I have shown a gasolene tank or container proper protected by a covering constructed in such manner that a puncture through it will be come automatically sealed, and that I have also shown a gasolene pipe connected to the tank and protected by such a covering as l have disclosed. lt is obvious, therefore, that this rubber covering may be applied notonly to tanks but to the-pipes in which gasolene -is held or through which vgasolene or like liquids pass, and the word container as used in the appended claims is intended to cover any pipe, duct, tank, reservoir, or like element for the. conduction or carriage ofl liquids of the benzene group'.

While l have illustrated certain details of construction which, in practical trials, have found to be particularly Valuable, yet l do not wishto' be limited to'this, as it is obvious that many changes might be made in the form of the invention without departing from the spirit thereof.

Having described my invention, what 1 claim is l. The combination with the wall of a liquid fuel container, of a covering therefor including a layer of rubber vulcanized to an extent whereby it is rendered insoluble in they liquid contained in the container, but

swelling relatively rapidly when moistened' therewith.

- 2. The combination with the wall ofl a liquid fuel container, of a covering therefor comprising an inner layer insoluble -in the liquid contained in the container and swelling when moistened therewith, and a relatively outer layer of material semi-soluble in said liquid and swelling when moistened therewith, the first named layer swelling more slowly than the second named layer.

3. rThe combination with the wall of a rapidly I liquid .fuel container, of a covering therefor compr1sing a layer disposed-next to the wall terial which will swell slowly when mois tened with the liquid contained in the tank, and an intermediate layer of elastic material which will swell rapldly when moistened with the liquid contained in the container and form a pasty mass between ,the inner and outer layers by the action of said liquid when the 4covering and'tank arepunctured.

5. The combination with the wall of`a liquid fuel container, of a covering therefor comprising inner and outer layers of fully cured sheet rubber, and an Vintermediate layer of slightly vulcanized. rubber.

y6. The combination with, the wall of a liquid fuel container of a covering therefor, comprising an inner layer of fully cured sheet rubber and a -relatively outer layer of slightly vulcanized rubber.

7. A. metal fuel container having thereover a covering comprising outer andl inner layers of fully cured\rubber, intermediate, layers of slightly vulcanized rubber, and a sheet of textile fabric disposed between the intermediate layers and to which said intermediate layers are'cemented, the first named innermost layer being cemented to the metallic container and the outermost inclosing the container, the envelop including a layer of rubber cemented to the container over substantially its entire surface, the rubber of the layer being vulcanized to a degree where it is rendered substantially insoluble in liquids of the benzene group and caused to swell relatively rapidly on contact with said liquids, to thereby close a perforation therethrough and throu'gh the container.

9. A metal fuel container and an envelop inclosing the container and including a layer of rubber exterior to the container, the rubber of the layer being vulcanized to an extent whereby it is rendered pastyupon an infiltration of a liquid of the benzene group through a puncture through the rubber and the container and caused to swell relatively rapidly bycontactwith the said liquid to thereby close the puncture.

10. The combination with the wall of a layer of material insoluble in liquids of the benzene group, but swelling upon a puncture of the layer` and the container and upon the consequent moistening of the layer by the liquid contained in, the container, a relatively outer layer of material semi-soluble in liquids of the benzene group and swelling rapidly when moistened therewith'as by the liquid seeping tlirough the puncture to thereby close the puncture, and a relatively outer layer of fabric insoluble in said liquid.

11. rlhe combination with the wal-l of a fuel container, of a self' puncture sealing covering therefor comprising a plurality of layers of rubber, the layers having different degrees of vulcanization, one of said layers being relatively insoluble in the liquid cony tained in the container but swelling slowly when moistened therewith and another of" said layers being semi-soluble in the liquid contained in the container but swelling rapidly when moistened therewith.

of means for self-sealing a puncture through the container comprising a layer of material on the exterior of the container swelling relatively quickly on contact with a liquid of the benzene group in the container without dissolution, to close the puncture therethrough.

13. The combination with the wall of va liquid fuel container, Vof a'covering therefor cemented to the container wall over its entire surface and comprising a layer of rubber on the exterior of the container vulcanized to an extentiwhere it is rendered substantially insoluble in a li uid ofthe benzene group and swellsrelatively rapidly when moistened with said liquid to thereby close a puncture vthrough the container -and the layer, and a layer of fabric to which said layer of rubber is attached over its entire surface. 14:..The combinationwith the wall of a liquid fuel container, of a covering therefor including a -layer of rubber vulcanized to such an extent that it is rendered insoluble andwill swell relatively rapidly-when moistened with a 'liquid vof the benzene group to thereby 'cause -the 'closure' of a puncture through vthe container andthelayer of rub-- ber, and a layer Aof textile fabric cemented` to the 'container wall and to which the layer of rubber is cemented. l j A fr 15. The combination-with the wall of a liquid fuel container, of a covering-therefor including a layerjof fabric 'and a'layerof rubber to Vwhich the fabric is caused' to vadhere, the -rubber being vulcanized to an extent whereby itis rendered substantially ini soluble in but swells quickly when moistened with a liquid of the benzene group to thereby close a puncture through the container and said layer.

.16. The combination with the wall of a moistened with a liquid of the benzene 1 group, said covering being cemented to the ontainer over substantially its entire suraoe.

. 17. The combination with the wall of a liquid fuel container, of a covering therefor including a plurality of layers of rubber with the said layers being vulcanized to an extent whereby it is rendered insoluble in the liquid contained in the container but swelling when moistened therewith, and another of said layers being vulcanized to an extent where it will become pastyand swell upon being moistened with liquid in the container, the layers being' cemented to each other over their entire surface and the cover being ceniented to the container over vits entire sur- 12. The combination with a fuel container,

means for localizing the infiltration *of gasolene through the rubber when the container is punctured.

19. rl`he combination with the` wallof a liquid fuel container, of a covering therefor u including a layer of rubbervulcanized to an extent where it is rendered insoluble in liquid of the benzene group but swells rapidly'when moistened therewith,'and a thin layer of cementi'tious material'holding the rubber to the container wall, said cementitious material being brittle.

'20. The combination with cluding a layer of rubber vulcanized to an extent where it is rendered insoluble inA the. wall of a Vliquid fuelcontainer, of a cover therefor incemented' to the container over, substantially its entire surface bya varnish'insoluble in iuids ofv the benzene group, sai'd varnishy n v thus acting .to localize the infiltration of liquid into said layer upon a puncture ofl the .container and cover.

liquid fuelcontainer, of a cover therefor including a'layer of r'ubbervulcanized to an 22. 'rhecombination with the wan of a.

21. rIhe combination with 4'the wall ofa' extent whereby it is rendered insoluble to liquids-.of the benzene group butswelling when moistene'd therewith, said layer being cemented over substantially its entire inner.

meegeven l liquid fuel container, of a cover therefor including a layer of rubber'vulcanized to an extent whereby it is rendered insoluble to liquids of the benzene group but swelling when moistened therewith, said layer being cemented over substantially its entire inner surface to the wall of the-container by shellac which is insoluble in liquids ofthe benzene group..

23. The combination with the wall of' a liquid fuel container, of a covering therefor including a layer of rubber vulcanized to an extent such that it has maximum expansibility when exposed to vfluids of the ,benzene group and is rendered substantially insoluble in the liquid containedv in the container self-sealing fuel container, of a covering therefor including a layer of caoutchouc vulcanized to such an extent that it is of maximum elasticity and tensile strength, said rubber being linsoluble in the liquid contained in the container but swelling relatively rapidly when mostened therewith.

1n testimony whereof ll hereunto afx mysignature in the presence of two witnesses.

- GEORGE J. MURDOCK.

Witnesses: v

J. P. MURDOCK, WM. J. MURDooK. 

